The invention is directed to an apparatus for the electropolishing of the inner surfaces of metallic tubes.
The process of electropolishing has been known for many years but it is only recently that it has matured into industrial usage. By electrolytic removal of material from metal surfaces which are connected as the anode in an electrolyte there is obtained a very smooth, clean, semi-polished surface condition.
The electropolishing process finds widespread use in the production of polished metallic samples where a high surface quality is required. However, it also is used industrially for the production of very valuable semifinished products. Thus, for example, nuclear fuel element jacket tubes are electropolished externally after they are loaded with fuel and welded closed. A corresponding quality also is required for the tube inner surface. However, previous attempts to polish the inner surface of tubes electrolytically have led to unsatisfactory results. Uniformity of the surface quality was achieved and made reproducible only with great difficulty. Hence, to improve the tube inner surface quality, one resorted to the known processes of etching or sanding with air.
These known operating processes for polishing the inner surfaces of tubes have great disadvantages both economically and also ecologically. They require a high expenditure of manpower, a high consumption of etching solution and accordingly a high expense for processing or for conditioning waste solutions. Furthermore, there results a great amount of dust with air sanding and that process obtains only a non-uniform, difficultly reproducible surface area quality of the tube inner surfaces.
Therefore it was the problem solved by the present invention to produce apparatus for the electropolishing of the inner surfaces of a tube with which there can be produced a uniform polishing.